Charging control in LTE (Long Term Evolution) is performed by a policy and charging rules function (PCRF) and a policy and charging enforcement function (PCEF) that is provided in a PDN gateway (P-GW: Packet data network Gateway) for connecting to an external packet data network (NPL 1).
For example, as shown in FIG. 1, a PCRF in a mobile core network determines policy information and charging rules to apply to user packets, and PCEFs in a plurality of P-GWs notify the numbers of packets, which are counted by them individually, to the PCRF as information for charging.
Moreover, in a communication system disclosed in PTL 1, a call connection method is adopted for reducing the load on a PCRF server. That is, a selector PCRF server and a plurality of provider PCRF servers are provided, and the selector PCRF server sends a resource request to each of respective provider PCRF servers on a caller side and a callee side, thereby reducing load.    [PTL 1] Japanese Patent Application Unexamined Publication No. 2009-188961    [NPL 1] 3GPP TS23.203 v11.6.0 (2012-06)